Formulation of a drug into an edible medication, such as a chewable tablet or confection, can increase patient acceptance of the medication, especially animals, who tend to resist swallowing hard tablets or capsules. Unfortunately, many drugs and other active ingredients (collectively, “actives”) have a strongly bitter or otherwise unpalatable taste, making chewing them unpleasant.
Flavorings are commonly added to chewable medications to enhance their palatability. For example, a veterinary medication might include animal product-based flavorings such as uncooked dried meat parts such as beef, pork, chicken, turkey, fish and lamb; organ meats such as liver; meat meals, bone meals and ground bone; and animal-derived food such as casein, milk (which may include dry forms and lowered fat forms, such as dry skim milk), yogurt, gelatin, cheese and egg (collectively, “animal origin flavorings”) may be utilized.
However, use of many animal origin flavorings (especially of meat, poultry or seafood origin) risks exposure to infectious agents, not only to the recipient of the drug, but also through contamination of manufacturing equipment on which the flavored dosage units are made. For this reason, manufacturing facilities that prepare pharmaceutical products with animal origin flavorings are often devoted exclusively to their preparation, at a correspondingly greater cost than would be incurred if manufacturing could be performed in a facility capable of concurrently processing multiple products.
Texture is also an issue for chewable medications. One of the most commonly used form for chewable dosage units is the compressed tablet, whose ingredients (including the actives and inactive ingredients such as binders) can make the tablet gritty or otherwise unappealing, especially to animals. Thus, a preferred alternative dosage form for use especially with animals is the “edible soft chew,” generally a meat-like mass or chunk also widely found in consumable pet treats, having a softness similar to a cooked ground meat patty.
Edible soft chews are typically manufactured by blending and extrusion. Pre-mixed ingredients are introduced into an extruder barrel with a screw therein, then mixed, coagulated, expanded and sheared into a blended mixture, followed by application of additional heat if a harder texture is desired, or water has been introduced into the mixture. Water introduced into the mixture must generally be of pharmaceutical grade, as it will be retained within the mixture. The blended mixture is then formed into a desired shape on a die plate, then cut into individual units.
The heat generated during the extrusion process can cause deterioration in the stability (potency or integrity) of the active in the mixture, causing the effective dose provided by each unit formed to vary. In particular, the heat from compression exerted during extrusion, especially auger extrusion can exceed the melting point of many compounds. Consistency of texture, shape and weights of the chews from batch to batch of extruded material can also suffer.
There is a need, therefore, for a method of manufacture for edible soft chewable medications in which the blending of actives into the chew mixture is achieved without generation of heat at a level that would cause the active to wholly or partially degrade. Preferably, the method would be performed without application of any heat above room temperature to the mixture or formed product. It is also desirable that the chews be susceptible to manufacture without use of costly, pharmaceutical grade water as an ingredient. There is also a need in the art for a edible soft chew medication whose taste appeals to animals without use of ingredients that may include infectious agents or contaminants. Further, it is highly desirable for the manufacturing means employed to produce chewable medications to do so in a manner that ensures consistent chew weights, texture and active dosages.